Weekly Shōnen Sunday (Japanese: 週刊少年サンデー,Hepburn: Shūkan Shōnen Sandē) is a weekly shōnen manga magazine published in Japan by Shogakukan since March 1959. Contrary to its title, Weekly Shōnen Sunday issues are released on Wednesdays.

Despite its name, Shōnen Sunday was originally published on Tuesdays of each week, switching to Wednesdays in 2011. The "Sunday" in the name was the creation of its first editor, Kiichi Toyoda, who wanted the title to be evocative of a relaxing weekend.

Weekly Shōnen Sunday's mascot, Issue 1991-#37

Shōnen Sunday's distinctive "pointing finger" that appears in the lower corner of every page on the left side of the magazine made its subtle debut in the 4/5 issue from 1969. This understated feature, ever present but easily overlooked, was referenced as a plot element in 20th Century Boys. Sunday's more noticeable mascot, a helmeted fish debuted in the 1980s.

In a rare event due to the closeness of the two magazine's founding dates, Weekly Shōnen Sunday and Weekly Shōnen Magazine released a special combined issue[4] on 19 March 2008. In addition, other commemorative events, merchandise, and manga crossovers were planned for the following year as part of the celebrations.[5] The book Shonen Sunday 1983 was published on 15 July 2009 to celebrate the anniversary and the magazines heyday. It reprints manga from 1983, such as Urusei Yatsura and Touch, and has interviews with their creators as well as artists who were inspired by the series from that period, such as Gosho Aoyama.[6]

To celebrate Weekly Shōnen Sunday's 55th anniversary, 55 new manga series were launched in the print and online magazines Weekly Shonen Sunday, Shonen Sunday S, Ura Sunday, and Club Sunday throughout the year beginning in March 2014.[7]